Stirrers for stirring a substance, such as a fluid or granular material comprised in a vessel, are used in a wide range of applications. These applications comprise performing chemical or biochemical tests and experiments in research, laboratories, hospitals etc. The stirrers comprise a stirring device, which is submerged in the substance and which can have all kind of shapes, depending on the characteristics of the substance. Traditionally, a capsule-shaped or bean-shaped stirring device is widely used, but many new designs are available to improve stirring torque and efficiency. The stirrer conventionally comprises a powering device for contactlessly, e.g. magnetically powering the stirring device,
In a stirring application, there is often a need to measure one or more parameters related to the substance to be stirred. These parameters may comprise all kinds of quantities, such as physical or chemical quantities. Some common examples of such parameters are a temperature or an acidity.
A known solution is to measure these parameters making use of one or more measurement instruments. The instrument is equipped with a separate or built-in sensing probe which is positioned in the substance. A disadvantage is that mechanical collisions might occur in the substance between the stirring device, which is making a stirring movement, and the sensing probe or an other part of a measurement instrument. An other major disadvantage is that the presence of the probe will have an influence on the process or processes taking place in the substance. The physical presence of the probe can, for example in case that the parameter is a temperature, have a direct influence on the temperature of the substance itself by means of the mass and temperature of the probe, or have an indirect influence, such as disturbing a temperature dependent chemical reaction, by a local or global change in the temperature of the substance because of the presence of the probe.
A known solution to overcome the above disadvantages when using a measurement instrument is to position the probe outside of the substance. This however has a disadvantage of a lower accuracy, because of the physical distance between the probe and the substance. Also a disadvantage is that it is not able to detect processes that are taking place inside the substance. Again making use of the example that the parameter is a temperature, chemical reactions comprise so called endothermic and exothermic reactions. By measuring a temperature of a substance using a probe which is positioned outside the substance, local temperature changes inside the substance can hardly be detected, making it difficult to monitor from outside of the substance if, and to what extent, reactions are taking place.
The above disadvantages especially arise in high-speed experimentation equipment, which is e.g. used in petrochemical and pharmaceutical industries. High-speed experimentation equipment comprises a number of units, in which reactions can take place. By varying initial conditions for these reactions, optimal conditions can be quickly identified by performing a number of experiments in parallel. To be able to achieve a high time-efficiency in performing these experiments, so called blocks are known, which comprise a large amount of similar or identical units, each provided with many functions, such as stirring, heating and cooling. Because of the requirements to quickly as well as accurately perform a large amount of reactions, and at the same time accurately measure one or more parameters for evaluation and selection, the requirements for accurate and reliable measurements are high and can hardly be met when making use of the above solutions.